What device demonstrates Earth's magnetic field?

• A. Bar magnet
• B. Compass
• C. Refrigerator magnet
• D. Electric coil

Answer: (B)

Earth’s magnetic field surrounds the planet and can be sensed by a small magnet freely able to rotate. A compass uses a tiny magnetized needle that aligns with the direction of that field, so it points toward magnetic north and shows the field’s presence and direction in the real world. The other devices each relate to magnetism in different ways: a bar magnet reveals the field around that specific magnet, not Earth’s global field; a refrigerator magnet is just a magnet used for sticking items and doesn’t demonstrate Earth’s field; an electric coil creates a magnetic field when current runs through it, illustrating electromagnetism rather than Earth’s natural field. So the compass best demonstrates Earth’s magnetic field by responding to it.